The most accomplished hitter on the Royals’ roster sat behind a bank of Lenovo ThinkPads inside the visitors’ clubhouse Tuesday at Petco Park and pored over video. The schedule for Billy Butler that night called for one at-bat at an undetermined time, the plight of a designated hitter in a National League city.

The most accomplished hitter on the Royals’ roster sat behind a bank of Lenovo ThinkPads inside the visitors’ clubhouse Tuesday at Petco Park and pored over video. The schedule for Billy Butler that night called for one at-bat at an undetermined time, the plight of a designated hitter in a National League city.

Later that night, he made it look easy. He rifled an RBI double for an 11th-inning insurance run. But his unease was legitimate. He sat during each game in San Diego as Eric Hosmer manned first base. Hosmer plays Gold Glove defense; he boomed his first homer of the year on Monday, scored the winning run on Tuesday and amassed four RBIs in Wednesday’s series victory.

Butler caught this action from the dugout. To Butler, three days off as a position player was equivalent to a starting pitcher taking two weeks off. The timing frustrated him. During the last home stand, Butler batted .381 with a 1.010 on-base plus slugging percentage. He accumulated three multihit games; in his previous 24 outings, he had multiple hits only four times.

With the bench beckoning, he fretted that his thawing process would halt.

“I’ve been really hot,” Butler said. “I’ve been known to stay on hot streaks for an extended amount of time. Unfortunately, the way to cool a hot hitter off is to not give him at-bats. Hopefully that’s not what happens. There’s nothing I can do about that.”

Butler understands the reality — “we’re designed for American League rules,” he said — and he is the most specialized outcrop of that construction. As they have for years, the Royals will face this dilemma again when they visit St. Louis, Arizona and Colorado later this summer.

When the team plays in National League parks, they must use Butler as a pinch hitter. His value in the field is negligible, despite a commitment to improvement this last spring training. The topic is a touchy one with Butler. He is prideful about his defense, maligned though it may be.

Earlier this season, manager Ned Yost hinted that Butler might start at first base if the team faced a left-handed pitcher. San Diego started two southpaws to begin this series. When Butler walked into the clubhouse on Monday afternoon, he thought he might need his glove. The lineup told him otherwise. He received no notice from his manager.

“I feel like letting your players know what you have them doing, or something like that, it’s not too much to ask,” Butler said. “But maybe it’s tougher on him, too, because we’re not used to interleague. Maybe he was still thinking about it. I don’t know.”

Butler’s suspicion was accurate. Yost explained he did not settle on his lineup until late Monday morning. The team experimented with Hosmer in right field last season. But he kept Hosmer at first for the opening round of interleague this year.

Yost offered a position that was somewhat counterintuitive: Because his team was struggling to score, they were willing to sacrifice offensive potential for defensive certainty.

“When you’re struggling to score runs,” Yost said, “the last thing you want to do is not be in a position to keep them from scoring runs.”

Butler did not fit into this picture. And he understood lobbying to be in the lineup would be counterproductive.

“He knows I want to play,” Butler said. “I don’t want to be sitting. I don’t think he wants to be sitting me, either. That’s his decision to make. Like he says, he’s putting a defensive lineup in there. He’s the skip. He’s the manager. That wouldn’t be the good team thing for me to do, to go in there and say something.

“I think it goes without saying that I want to play. And I feel like I’ve earned the right to play. But he still makes the lineup. My numbers over the years speak for themselves. You don’t really have to go in there and argue for yourself.

“Anything you ever go in there and say, it never really turns out good. You really gain nothing from that. It turns out bad. It gets turned on you, as you’re a selfish player, or whatever. I’ve talked to managers before, in the past, and that’s just my experience with it.”

Yost did not trust Butler’s glove in the field this week in San Diego. But he does not fret about his bat in Seattle.